/**
 * Service Worker — 今天吃啥 PWA
 * 策略：静态资源 Cache First，数据 Network First，图片 Cache First
 */
const CACHE_STATIC = 'weinan-dishes-v1';
const CACHE_IMAGES = 'weinan-images-v1';

const STATIC_FILES = [
  '/',
  '/index.html',
  '/style.css',
  '/app.js',
  '/dishes.json',
  '/manifest.json',
];

// Install: 预缓存核心静态资源
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_STATIC).then((cache) => {
      return cache.addAll(STATIC_FILES);
    })
  );
  self.skipWaiting();
});

// Activate: 清理旧缓存
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((keys) => {
      return Promise.all(
        keys.filter((k) => k !== CACHE_STATIC && k !== CACHE_IMAGES)
          .map((k) => caches.delete(k))
      );
    })
  );
  self.clients.claim();
});

// Fetch: 按资源类型分策略
self.addEventListener('fetch', (event) => {
  const url = new URL(event.request.url);

  // 图片: Cache First
  if (url.pathname.match(/\.(jpg|png|svg|webp|ico)$/i)) {
    event.respondWith(
      caches.match(event.request).then((cached) => {
        const fetchPromise = fetch(event.request).then((response) => {
          if (response.ok) {
            const clone = response.clone();
            caches.open(CACHE_IMAGES).then((cache) => cache.put(event.request, clone));
          }
          return response;
        });
        return cached || fetchPromise;
      })
    );
    return;
  }

  // dishes.json: Network First（保证数据新鲜）
  if (url.pathname.endsWith('dishes.json')) {
    event.respondWith(
      fetch(event.request)
        .then((response) => {
          const clone = response.clone();
          caches.open(CACHE_STATIC).then((cache) => cache.put(event.request, clone));
          return response;
        })
        .catch(() => caches.match(event.request))
    );
    return;
  }

  // HTML/CSS/JS: Cache First（App Shell）
  event.respondWith(
    caches.match(event.request).then((cached) => {
      const fetchPromise = fetch(event.request).then((response) => {
        if (response.ok) {
          const clone = response.clone();
          caches.open(CACHE_STATIC).then((cache) => cache.put(event.request, clone));
        }
        return response;
      });
      return cached || fetchPromise;
    })
  );
});